Thursday, January 22, 2009

Everyone knows that dieting and losing weight is hard, especially for women. It's like our bodies are hard-wired to fail - and, perhaps they are. At least that is one interpretation of a new study coming out of the Brookhaven National Laboratory this week, set to be published in PNAS shortly.

The researchers looked at the PET scans of men and women after 20 hours of fasting at rest, when looking, smelling, and drooling over their favorite food, and when that food is presented to them but they are told not to think about it. All of the subjects reported feeling less hungry for the food when they tried not to think about it, but their brains told a different story.

The scans to the right show the differences in brain activity between the conditions of wanting the food and wanting the food but forcing themselves to think about something else. The top row is the women, and the scans aren't colored because there was no difference between the conditions. Whether they tried to distract themselves or not, their brains activated the same areas involved in the emotional regulation, conditioning, and motivation to eat. The second row, instead, are the men's scans - the blue areas are parts of the brain which were significantly less active when forcing themselves not to think about the food. The third row compares the women and the men, with the orange areas indicating where men showed decreases in brain activity that the women didn't.

In other words, when the men tried not to think about food, they succeeded in changing their brain chemistry and actually decreased their desire for it, while the women didn't. This might explain why it always seems easier for guys to lose weight - when they put their mind to it, it listens. This study is the first that has found gender-specific differences in the connection (or lack thereof) between emotion state and brain activity.

“The finding of a lack of response to inhibition in women is consistent with behavioral studies showing that women have a higher tendency than men to overeat when presented with palatable food or under emotional distress... This decreased inhibitory control in women could be a major factor contributing to the observed differences in the prevalence rates of obesity and eating disorders such as binge eating between the genders, and may also underlie women’s lower success in losing weight while dieting when compared with men," said lead author Gene-Jack Wang in the lab's press release.

Researchers think that the differences found may be due to sex hormones like estrogen, which have already been shown to affect weight, fat distribution, and even caloric intake. Other molecules that regulate eating behavior might also be involved, and clearly further research into this effect is needed.

In the meantime, we women can honestly complain that it's not our fault we can't shed those holiday pounds. After all, you boys have it easy - your brains actually forget about food when you want them to. Stupid men... why must women always have the short end of the stick?

12
comments:

Speaking for my fellow Y-chromosomers, I'd like to offer a few thoughts. First of all, there are quite a few of us who believe that the vast majority of women only think they're carrying extra weight when their bodies are really just fine. (Of course I realize it is largely a male-dominated advertising industry that pushes the idea that all women need to be able to wear size-zero clothes.)

Secondly, there are plenty of men who could stand to lose a few pounds, and this study is just a way of saying that they have no excuse.

And finally, we all put on a few extra pounds during the holidays. What do you think baggy sweaters and big heavy coats are for? To keep us warm?

Christopher: One question... does my labcoat make me look fat? J/k. I was actually wondering, while thinking about this article, if there's some reason women's brains were more focused on food - a social cause, that is. By that I mean some sort of conditioning, that as a girl you're supposed to think about weight, how you eat, etc, so it's harder as an adult to simply put those things out of your mind. Similarly, if the test brought up issues about sex or muscle, the women might be able to "distract" themselves more easily than the men...

Bjorn: Now, now, it'll be alright. Those meanies can't hurt you here.

Lilian: That's an interesting thought, and I would say I am definitely incapable of thinking of nothing. trust me, I've tried. The men I've been with, however, seem to think of nothing often - I ask "What are you thinking?" They say "Nothing." I say "That's impossible, you must b thinking something." They swear up and down, (rather annoyedly for that matter) that they were really not thinking of anything. Maybe you're on to something...

I remember reading an article last year in Discover magazine about something similar, but no behavioral study had backed it up. The scientist had done a weight study, and showed that even on the exact same diet and exercise plans, men burn more and lose weight more quickly. They also concluded that it had to do with estrogen, and may be a by-product of evolution. Once upon a time, women's bodies may have developed a strategy for surviving famines much better than males do, in order to keep producing babies even when food sources were low. Not too encouraging in our time when food is OVER-abundant... but rest assured in a shortage, we would out-live all the dudes, LOL. Thanks for sharing this!! It puts some more pieces of the puzzle together for sure...

"I ask "What are you thinking?" They say "Nothing." I say "That's impossible, you must b thinking something." They swear up and down, (rather annoyedly for that matter) that they were really not thinking of anything."

I doubt they were really thinking of nothing. They were probably thinking of breasts - someone else's. Or something of that nature.

Or perhaps that's just me?

No, I'm pretty sure that most dudes are thinking about breasts most of the time.

I guess I should clarify. The left and right columns are two different cross-sectional views (look closely - they look different). So the rows are showing what I described, the columns show two different parts of the same brains... does that make sense? (check out the link to the press release if you want clarification)

I doubt they were really thinking of nothing. They were probably thinking of breasts - someone else's.I started to say "They're not necessarily thinking of someone else's" and then I realized that made it sound like men might be thinking of their own breasts. Admittedly in some cases this is possible, but highly unlikely. Anyway we're not always thinking of breasts, but the answer "Nothing" is usually a way of trying to politely say, "We're thinking about something really stupid that we're embarrassed to admit to."

Christie, your lab coat doesn't make you look fat, but I have to say they're not exactly flattering on anyone. Maybe they should come in black. I've heard black is very slimming, and if black is slimming, white is, well...

So the guys I've dated not only lie about what they're thinking, they then get all defensive and tell that I'm being crazy not to believe them knowing they're lying? And you men say women play mind games...

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I started this blog mostly because of my friend Allie. She's on her way to a masters in Journalism, and she got assigned to write a blog for one of her classes. When she told me about it, I thought"wow, good idea."

You see, I love to write, but as a scientist very little of my day-to-day writing is interesting or legible to anyone who isn't a scientist. So this lets me write in a way that is actually fun to read - I know, novel.

Anyhow, if you want to why it's called "Observations of a Nerd," read this.